Lubricant containing an aliphatic amine salt of monoalkyl ester of a dimeric acid



LUBRICANT CONTAINING AV ALIPHATIC gil flzlE SALT, 0F MONOALKYL ESTER Herschel G. Smith, Wallingford, and Troy L.- Cantrell,

and other deficiencies of uncompounded mineral oils, various agents known as addition agents, additives are commonly incorporated in tobe used.

The compounds of the present invention form extraordinarily efiective corrosion inhibitors which may be used as improvement agents or additives for mineral oils and particularly for lubricating oils such as turbine oils which are required to function in the presence of water. compounds includethe class of amine salts of or improvement agents the particular mineral oil of dimeric acids, these acidsbeing derived from unsatu-' rated fatty acids containing from 6 to 22carbon atoms and havingfrom 2 to 3 ethylenic linkages per molecule.

The invention also includes methods of making the fore-.

going. compounds and in addition includes mineral oil compositions containing compounds of the above-identifiedtclass. 'aThe compounds of the present inventi-on may in genera al be represented by the generic formula:

. H R; i l o N Ri CnHmi-a Rs o-o-m where v United States Pa 0 More tralizing the monoalkyl ester 2 is the acyl residue of a dimerized dior trienoic fatty acid,

to 42, where x mary, monohydric alcohol. An amine salt of the resulting monoalkyl ester reaction product is formed by neuwith the desired aliphatic amine. The partial esterification is effected in conventional vmanner and under conventional conditions by reacting equimolar'proportions of alcohol and dimerized acid. While esterification may proceed slowly at room temperature, the reaction is' catalysts such as hydrogen chloride, sulfuric acid, or an aromatic sulfonic acid, such as p-toluenesulfonic acid. The reaction may be driven to substantial completion by removing one of the products of reaction. The use of a monohydric alcohol having a boiling point above that of Water is advantageous, since this expedient lends itself to completion of the reaction by removal of the water of esterification through simple distillation; Removal of the water of esterification may be facilitated by mechanical agitation or by bubbling an inert gas, e. g, nitrogen, through the reaction mixture. 7

The final amine salt reaction product is formed by neutralization or substantial neutralization of the monoalkyl esterwith approximately equimolar proportions of the desired amine. In practice, it has been found convenient simply to add'sufiicient amine to raise the pH of the reaction product to between about 6.5 and about 7.5. The neutralization of the monoalkyl ester of the dimer acid takes place spontaneously at room temperature with the evolution of heat in the instance of primary amines.

heat is normally required to accelerate the reaction 1n the instance of secondary or tertiary amines. Care should be exercised, when the neutralization is efifected' with primary or secondary amines, to prevent the temperature of the reaction mixture from rising above the boiling point of water, in order to avoid amide formation. v l The dimerized acids referred to above are dimers,

i. e., bimolecular addition products of conjugated or unconjugated dienoic to trienoic fatty acids having from 6 to 22 carbon atoms before dimerization. Dimeric acids of the foregoing derived from dienoic'and trienoic fatty acids are 'wellknown and can be prepared by conventional methods which form no part of this invention.

More particularly, dimerized acids capable of forming the compounds of this invention are prepared from dior trienoic fatty C ",,COOH, where n is an integer of from 5 to 21 and x is 3 or 5. As will be evident, such monomeric acidscontain from 6 to 22 carbon atoms and may contain 2 or 3 ethylenic linkages as the ratio of carbon to hydrogen increases, i; e., as x increases from 3 to' 5. Dimerized acids corresponding to the addition products acids therefore may be defined by the genericformula: 1

Patented Apr. 8, 1958' are prepared by first conventional esterification acids having the generic formula.

where n is an integer of from 10 to 42 and where x is an i even integer of from 6 to 10. These dimeric acids are therefore dibasic or dicarboxylic acids having from 12 to 44 carbon atoms.

Representative members of the class of dimerized acids capable of forming the compounds of this invention are dimers of dienoic acids such as sorbic (hexadienoic), linoleic (octadecadienoic), humoceric (nonadecadienoic) and eicosinic (eicosadienoic) acids. Dimers of trienoic acids, for example, linolenic and eleostearic (octadecatrienoic) acids also may be used.

It is not necessary that both of the unsaturated fatty acid molecules of the bimolecular addition product be identical. Dimers of mixed composition such as those obtained by dimerizing mixed dienoic, mixed trienoic or mixed dienoic and trienoic acids such as may be derived from certain naturally occurring drying oils are quite satisfactory.

Dienoic and trienoic acids having 18 carbon atoms, especially those having conjugated ol'efinic linkages, are preferred for reasons of economy of procurement, ease of reaction and the general excellence of the additives prepared therefrom.

As indicated, alcohols capable of forming the abovementioned monoalkyl esters are the saturated aliphatic,

primary, monohydric alcohols, and especially those of lower molecular weight, of which ethyl, hexyl and octyl alcohols are representative. The use of higher alcohols is included by the invention, but such alcohols produce no additional advantage other than a slight increase in the oil-solubility limit of the final reaction product. The alcohols included by the invention may be either straightor branched-chain. Lower monohydric alcohols having a boiling point above that of water, e. g., butyl, amyl or octyl, are especially the esterification reaction to be carried to completion by distillation of the Water formed during the reaction, and also since the oil-solubility of these alcohols render it possible to carry out both the esterification reaction and the neutralization reaction in a mineral oil solution. Such procedure is often advantageous, since it avoids localized overheating of the reactants, and since the product resulting from this procedure is in the form of a mineral oil concentrate containing a relatively high proportion, i. e., up to the solubility limit, of the additive t composition. Such mineral oil concentrates of the additives are desirable, since solution of the additive in the ultimate carrier is often greatly facilitated thereby.

Aliphatic amines included for use in the invention are primary, secondary and tertiary amines least one aliphatic N-substituent having from 6 to 26 carbon atoms. The aliphatic N-substituent of the amines may be saturated or unsaturated, straightor branchedchain, and substituted with groups which do not adversely affect the oil-solubility of the final product. amines may in general be characterized by the general formula:

where R R and R are as defined above.

Illustrative of primary saturated aliphatic amines included in the scope of the invention are the straightor branched-chain alkyl amines such as hexylamine, hexadecylamine and hexacosylamine. The corresponding unsaturated amines such as hexenyl, hexadecenyl and hexacosenyl amines are representative of suitable unsaturated amines. Secondary and to the foregoing classes of primary amines may also be used and include not only amines having identical substituents such as dihexylarnine, dicyclohexylamine and tridecylamine, but also those having dissimilar substituents such as N,N-hexyl,octadecenylamine.

Preferred amines are the so called fatty amines, i. e., primary alkyl amines containing from 8 to 18 carbon suitable, since these alcohols permit 3 containing at 1 These tertiary amines corresponding atoms. Commercial mixtures of fatty amines such as those derived by conventional methods from naturally occurring substances such as coconut oil (cocoamine), palm oil and animal fats or the like are highly suitable.

Representative examples of the herein disclosed class of additive compounds are the octyl, lauryl, o'c'tade'cyl, octadecenyl, cyclohexyl and dicyclohexyl amine salts of ethyl, butyl, amyl, and octyl dilinoleate's and dilinolenates. The preparation of the herein disclosed class of cornpounds can be further illustrated by reference to "the following specific examples.

EXAMPLE I Eighty-eight parts by weight of amyl alcohol wereadmixed with 564 parts by weight of dimerized linoleic acid, and the mixture was heated, trapping off 18 parts by. weight of water, over a period of about 4 hours to, a mum temperature for the reaction mixture of 550 F.

The dimerized linoleic acid referred to was a commer cial dimeric polymer, manufa'ct'ured'by Emery Industries, Inc., of Cincinnati, Ohio, consisting essentially of dilinoleic acid:

The commercial dimer acid had the following physical properties: Physical state Straw-colored,

viscous liquid.

The reaction product of the tion reaction, consisting essentially of the monoamyl esters of dilinoleic acid, was cooled to room temperature, and approximately 133 grams of Armeen 81) were added. Arm-een 8D is a commercial mixture of primary amines, manufactured by Armour & Company of Chicago, Illinois, containing predominantly. octylamine together with minor proportions of hexyl and decyl amines and having a mol combining weight of 133 and a melting point of -13 C. The final reaction product, consisting essentially of the octyl, hexyl and decyl amine salts ofrnonoamyl dilinoleates, was a deep red-colored, viscous liquid having the following properties:

Gravity: API 19.1 Viscosity, SUV: Sec. 210 F; 436 pH Value, glass-calomel electrodes 7.5 Color, ASTM union 7.5

Elemental analysis of the reaction product gave the following results:

Analysis, ultimate, percent by wt.:

Sulfur 0.1 Hydrogen 12.2 Carbon 78.2 Oxygen 7.7

Nitrogen 1.8

maxiv above-described csterifi'ca' of amyl alcohol.

sired vehicle. Where oil compositions where the ployed as a fuel or. a lubricant but merely as a solvent vehicle. Exemplary of this type of composition are light .7 naphtha and similar solvents containing the novel compounds of this invention.

leaves an adherent tive on the article.

are highly effective small concentrations of these additives to EXAMPLE II To approximately 564 parts by weight of the dimerized linoleic acid of Example Iwereadded 88 parts by weight The mixture was heated under reflux over a period of 4 hours, and 18 parts by. weight of water were trapped oil the maximum reaction mixture temperature reached being; 550 F. The inonoamyl ester reaction product was cooled to room temperatureand one mol of Armeen CD was'added and the mixture stirred. The neutralization reaction proceeded spontaneously with the evolution of heat. ..Armeen CD is a commercial mixture ofprimary amines, also manufactured by Armour & Company, andderived in known manner from coconut oil. Armeen CD contains a predominant proportion of dodecylamine together with lesser proportions of octyl, decyl, teteradecyl, hexadecyl octadecyl and octadecenyl amines, has a mol combining weight1of 206, an1d has an approximate'melting point of21,C. The final product of the foregoing reaction contained predominantly the cocoamine salts of. monoamyldilinoleatesand was a deep red-colored, viscous liquid having the following properties: r

Gravity: API Viscosity, SUV: Sec. 210 F 400 pH value,-glass-calomel electrodes 7.5 Color, ASTM union 7.5

Elemental analysis of the reaction product gave the fol lowing results:

Analysis, ultimate,

Sulfur Hydrogen 12.4 Carbon 78.3 Oxygen Q 7.5 Nitrogen. c 1. 7

Amine salts of other monoalkyl esters of dimer acids may be obtained in'substantially identical fashion by the useof other of the disclosed dimerized fatty acids, alcohols and amines.

The reaction products resulting from the above-de-- scribed procedures, either alone or in the form of a mineral ,oil concentrate, may be incorporated in the dethe vehicle is a mineral lubricating oil, e. 'g., a turbine oil, the reaction products are em ployed in a minor proportionsuflicient to confer corrosion inhibiting properties 'uponthe latter. Normally from about 0.1 to'about 1.0 percentof the additive by weight of the composition is sulficient for this purpose, although greater proportions,'i. e, up to -2 or 3 percent by weight, are sometimes desirable and can be used. Examples of various mineral oils which can be benefited by the additives of this invention are gasoline, kerosene,

diesel fuel, furnace oil, motor oils, lubricating greases The invention further includes mineral solvent constituent is not emand turbine oils.

In such instances the compositions find use in the coating art, whereby metallic articles subject to rust or corrosion are brushed, dipped or sprayed with a composition comprising the solvent vehicle and the additive. Subsequent evaporation of the solvent As indicated above, the herein disclosed compounds corrosion inhibitors. This property of the compounds of this invention has been demonstrated by subjecting lubricating oil compositions containing the standard, accelerated corrosion tests ASTM D665-47T, procedures A and B. These tests are described in detail in the ASTM Standards of Petroleum-Products and Lubri- 6. cants, November 1948. Very briefly, procedure A of this'test involves immersion of a standard steel test 'rod' in an agitatedmixture of distilled water and the test oil maintained at atemperature of 140 F. for 48 hours. Procedure B is carried out in-substantially identical fashion except that a standard, synthetic sea water solution is substituted for the distilled water of procedure A. The corrosion inhibiting properties of theoil are determined by examination of the steel rod for rust or ,corrosion at the conclusion of the test.

The following specific examples are illustrativeofthe results obtainable by the compounds of this invention.

EXAMPLE III To a highly refined, highly parafiinicturbine oil base having an API gravity 'of between 30.5 land 32.5 and a viscosity of about 150 SUS at.100F., andwhich had been inhibited against oxidation, was added'0.15 percent by weight of the composition of the additive prepared according to Example I. Samples of the improved turbineoil and unimproved turbine oil base were tested according to procedures A and B, ASTM D665.47T. The

results of these tests are presented in the table below:

EXAMPLE IV To a turbine oil base in Example III was added additive prepared according to Example 11. The improved turbine oil and the unimproved turbine oil basewere each tested according to procedures A and B of ASTM D665-47T. The results of these sented in the following table:

Table B corrosion-resisting coating of the addi- Base on l te 0.15%

vY W Product oi Ex. II

Base 011.

Corrosion Test ASTM D665-47I, Procedure A,

Distilled Water, 48 Hrs;

Steel Rod, Appearance rustedbright. Area Rusted, percent 0. Corrosion Test ASTM D665-47T, Procedure B,

Synthetic Sea Water, 48 Hrs:

Steel Rod, Appearance sted- Area Rusted, percent 100 EXAMPLE V To separate samples of a turbine oil base of the same type described in Example III were added respectively 0.2 percent and 0.3 percent by weight of the dimerized linoleic acid described in Example I. These samples were bright. 0.

tested according to procedures A and B of ASTM D665-47T. The results of these tests are shown below.

of the same type as that'described" 0.15 percent by weight of the tests are pre- Table C Base Oil Base Oll plus 0.2% plus 0.3% by wt. Diby wt. Dimerlzed merized Linoleic Liuoleic Acid Acid Corrosion Test ASTM D665-47T, Procedure A, Distilled Water, 48 Hrs.:

Steel Rod, Appearance rusted. rusted. Area Rusted, percent 70 70. Corrosion Test ASTM D665-471, Procedure B, Synthetic Sea Water, 48 Hrs;

Steel Rod, Appearance rusted rusted. Area Rusted, percent 100 100.

Examination of Tables A and B indicates that low concentrations of the compounds of this invention impart extremely high corrosion inhibiting properties to oils, even under the exteremly severe conditions of the ASTM procedure B accelerated corrosion test.

Comparison of the results given in Tables A, B and C shows that our amine salt-monoalkyl ester derivatives produce as much as 100 percent improvement in results even when used'in concentrations as little as one-half as much as the parent dimer acid. The herein disclosed compounds also impart more persistent corrosion inhibiting properties to mineral oils than do the parent dimeric acids.

It is to be understood that the improved mineral oil compositions of this invention can be additionally improved by incorporation therein of other known additives in order to confer thereon other desirable properties, such as increased resistance to oxidation, increased stability, etc. Thus, there can be added viscosity index improvers, thickeners, bearing corrosion inhibitors, antioxidants, extreme pressure agents, foam inhibitors, dyes, sludge inhibitors, detergents, etc.

The additive compounds included by the invention also find utility as corrosion-inhibiting additives for various paints, varnishes, automobile undercoatings and the like. In the use of the agents of ths invention in the abovedescribed coating compositions, it may be desirable to employ these agents in substantially greater concentrations than are normally utilized in fuels and lubricants.

It will be understood by those skilled in the art that numerous modifications may be resorted to without departing from the spirit of the invention or scope of the appended claims.

We claim:

1. An amine salt of (1) an aliphatic amine having at least one N substituent containing from 6 to 26 carbon atoms and (2) a monoalkyl ester of a dimeric acid,

said 'dimeric acid being derived from an unsaturated fatty acid containing from 6 to 22 carbon atoms and having from 2 to 3 ethylenic linkages per molecule.

2. The compound of claim 1 wherein the unsaturated fatty acid contains 18 carbon atoms.

3. An amine salt of a primary alkyl amine containing trom 8 to 18 carbon atoms and a monoamyl dilinoleate.

4. A method of preparing an amine salt of a monoalkyl ester of a dimerized unsaturated fatty acid, comprising forming a monoalkyl ester by reacting substantially equimolar proportions of a saturated aliphatic primary monohydric alcohol and a dimeric acid derived from an unsaturated fatty acid containing from 6 to 22 carbon atoms and having from 2 to 3 ethylenic linkages per molecule, and forming an amine salt of said monoalkyl ester by neutralizing the same with an aliphatic amine having at least one N- substituent containing from 6 to 26 carbon atoms.

5. A mineral oil composition comprising a major amount of a mineral oil and a minor amount, suflicient to impart corrosion inhibiting properties to the composition, of an amine salt of (1) an aliphatic amine having at least one N- substituent containing from 6 to 26 carbon atoms and (2) a monoalkyl ester of a dimeric acid, said dimeric acid being derived from an unsaturated fatty acid containing from 6 to 22 carbon atoms and having from 2 to 3 ethylenic linkages per molecule.

6. The composition of claim 5 wherein the mineral oil is a lubricating oil.

7. The composition of claim 5 wherein the mineral oil is a turbine oil.

8. The composition of claim 5 wherein the unsaturated fatty acid contains 18 carbon atoms.

9. A mineral oil composition comprising a major amount of a mineral oil and a minor amount, suificient to impart corrosion inhibiting properties to the composition, of an amine salt of a primary alkyl amine containing from 8 to 18 carbon atoms and a monoamyl dilinoleate.

10. The composition of claim 9 wherein the amine salt is present in concentrations of from about 0.01 to about 1.0 percent by weight of the composition.

References Cited in the file of this patent UNITED STATES PATENTS 2,162,454 Guthmann June 13, 1939 2,366,013 Duncan Dec. 26, 1944 2,399,510 Rocchini Apr. 30, 1946 2,564,422 Barnum Aug. 14, 1951 2,587,546 Matuszak Feb. 26, 1952 2,631,979 McDermott Mar. 17, 1953 2,689,828 Smith et a1. Sept. 21, 1954 

5. A MINERAL OIL COMPOSITION COMPRISING A MAJOR AMOUNT OF A MINERAL OIL AND A MINOR AMOUNT, SUFFICIENT TO IMPART CORROSION INHIBITING PROPERTIES TO THE COMPOSITION, OF AN AMINE SALT OF (1) AN ALIPHATIC AMINE HAVING AT LEAST ONE N- SUBSTITUENT CONTAINING FROM 6 TO 26 CARBON ATOMS AND (2) A MONOALKYL ESTER OF A DIMERIC ACID, SAID DIMERIC ACID BEING DERIVED FROM AN UNSATURATED FATTY ACID CONTAINING FROM 6 TO 22 CARBON ATOMS AND HAVING FROM 2 TO 3 ETHYLENIC LINKAGES PER MOLECULE. 